Ryūji Kōno enters the narrative shortly after Hiroshi's departure to London, coinciding with Ami Nonomura's period of emotional vulnerability and depression. Appearing as a callous playboy, Kōno capitalizes on Ami's fragile state and seduces her during a nightclub outing arranged by her friends seeking to distract her. Later in the series, after Hiroshi briefly returns to formally end his romantic relationship with Ami, leaving her deeply saddened, Kōno transitions into the role of her boyfriend. While the progression of their relationship remains undetailed, his status as her boyfriend is established in the later stages of Ami's story.